In assembly plants for manufacturing vehicles, different types of conveying devices as well as of overhead conveying devices are employed. Based on the fact that assembly plants are individually adjusted to each type of vehicle to be manufactured and that the conveying devices are correspondingly configured, the overhead conveying devices under consideration are correspondingly individually designed and manufactured. Here, an overhead conveying device of the type at hand relates to those conveying devices below which at least enough free movement space remains to allow a person to freely walk below them. Usually, free headroom of at least 2.5 m or more is the aim so that forklift trucks or other transport vehicles are also able to cross below the overhead conveying device. Overhead conveying devices of this kind are also employed in order to obtain additional assembly space, wherein, standing on the floor, another conveying device or another kind of assembly machine, such as an assembly robot, may be arranged underneath the overhead conveying device. To integrate overhead conveying devices of this kind into a complete assembly plant in a building, it is common in the state of the art to put a supporting framework together from steel girders or the like for erecting the actual conveying device on-site in the building, wherein the struts and pillars are usually welded together on the construction site. This allows for an adaptation to the conditions at hand both with regard to the assembly plants and with regard to the facilities of the building, and assembly plants or building facilities already present can in particular be taken into account.
For a start, the generic overhead conveying device is intended for integration in an assembly plant for transporting vehicle components. The type of the vehicle components is irrelevant in this case. The substantial feature is that the overhead conveying device is integrated in a complete assembly concept, making it possible here to manufacture a vehicle by transporting the assigned vehicle parts. For this purpose, the overhead conveying device has a supporting framework and at least one conveying device.
Generically speaking, the supporting framework has a length greater than 5 m and a width greater than 2 m. The height at which the supporting framework of the overhead conveying device is affixed above the floor of the designated building is irrelevant for the invention at hand, but the free headroom below the supporting framework has to be at least 2 m so as to guarantee a suitable useful height below the supporting framework. The supporting framework itself is realized by longitudinally and/or transversely oriented or diagonally interconnected supporting beam elements. Said supporting beam elements are usually designed in the shape of rods and can have tubular profiles, T-girders or other shapes and they can be designed as traction girders, pressure girders or as girders under a bending moment.
The associated conveying device is mounted on the supporting framework and allows transporting corresponding vehicle components, the transport usually taking place along the longitudinal direction of the overhead conveying device.
Furthermore, the supporting framework comprises bearing means on which the overhead conveying device is borne in the assembly plant. It is initially irrelevant whether said bearing means are fixed bearings, mobile bearings or other types of bearings. The supporting framework is at least substantially supported on the bearing means in the direction of gravity and on counter-bearings being provided by the assembly plant or by the building.
The commonly found practice of putting the supporting framework together on site on the basis of the local conditions leads to structural calculations and a previous detailed construction of the supporting framework of the overhead conveying device usually not being carried out. Due to these insufficient calculations of the supporting framework, said supporting framework, for safety reasons, is usually designed with a significant oversize, which, however, does not guarantee that sufficient safety is given, either.
However, the design of an overhead conveying device known from the state of the art is particularly disadvantageous in the light of the high amount of time that is required for setting up the corresponding components in the assembly plant. During such setup works, the assembly plant is inevitably unavailable for other purposes in the area of the overhead conveying device to be constructed. In particular when making structural alterations to the assembly plant, switching from one design, for instance for manufacturing a particular vehicle model, to a new design of the assembly plant for manufacturing a changed vehicle model, this leads to undesired production downtimes while the overhead conveying device is being set up.